1/4" refrigeration tube vs water tube

[toofless one]

I built my boka with 1/4" refer tubing for the output line. i bought a 1/4" needle valve and the valve isnt big enough...home depot says thats all they got.

anyone else have this problem and if so how was it overcome?

do valves come in different 1/4" sizes??

[Dnderhead]

you shore that is arcon tubing? as arcon/refrigeration tubing is measured out side,,water is in side. so a valve for water should be two big.
measure your tube and let us know.

[ozone39]

valves in general come with different characteristics, for example: ball valves, available in 3/4 or full port configuration, they have good 100% seal on them (generally don't leak by when closed), but do not work good as a throttling valve. Gate valves: have a some what good throttling capability but suck when it come to not leaking by when they are closed, they are susceptible go particles building up in the seat and causing problems. Globe valves are a good throttling type valve but have a high friction co-efficient when fully opened, the media traveling through the valve makes a pretty drastic change in direction. They use a disk type seat (similar to a pressure reducing valve), thus giving them a good flow control type quality. Needle valves are general a very low flow type control valve. friction co-efficient is high. a 1/4" valve will have a valve seat sized around 1/8" or 3/32", so you automatically lose 100% capacity with this type of valve. If I where you I would up size the valve to 3/8" if you need full flow when opened %100, use reducers to adapt he valve to pipe..

[toofless one]

Well, i guess i can chalk this one up to lazy/stupidity/not being thorough enough...

Its a 5/16" line, not 1/4". Guess what else, home depot and other building supply outlets dont carry this oddball size. They asked my what i was trying to mcgyver.

oh well, i guess i will have to do some bastardization to make this work, seeing as how the nearest store is about 60 miles from me

[still crazy]

If theres nuff meat around the shoulder of your fitting dill out the opening to let ya slide your 5/16 tube into it and hit it with a dab of soilder.
Make sure your seat in your needle vale ain't rubber or you will cook it.

[toofless one]

good thinkin still. thats where i was gonna go next. either that or reduce the 5/16" to 1/4" and put the valve on it that way. i got a copper reducer that will fit with some very minor soldering

[olddog]

Your 1/4" tube should slide into your larger tube, just solder a bit in instead of a reducer.
If it does not slide in stretch the 5/16 with a center punch.

[toofless one]

olddog, sometimes you make me feel just plain stupid! That is so damned easy.


thats probably why im still a young pup

[olddog]

Glad to be a help.

[HookLine]

Gate valves: have a some what good throttling capability but suck when it come to not leaking by when they are closed,

It is true that gate valves do not seal as well as some other types of valve. But in our application (in a VM still) there is very low pressure on the valve seal, barely above ambient atmospheric pressure. I think the seal on my stainless gate valve is rated at 200 psi. Way more than enough for our purposes.

[gate valves] are susceptible to particles building up in the seat and causing problems.

That is also true. But we are not passing anything through them that contains any particles, just vapour/gas. They are also pretty easy to clean out.